Dental caries is essentially a microbial disease of childhood and is a major health problem in our society. Considering the bacterial nature of dental plaque and the current knowledge of the role of Streptococcus mutans in the etiology of dental caries, it is logical to predict that of all the approaches to the control of caries the antimicrobial route, especially the use of antibiotics could be one of the most effective. This proposal is concerned with an in depth study of the potential usefulness of highly specific antimicrobial agents, the bacteriocins, for the control of dental caries. In the first phase of this study we have identified a number of microorganisms which produce bacteriocins active against all serotypes of S. mutans. We have also isolated and partially purified two of these bacteriocins. In later studies these purified bacteriocins are to be tested in animal models to determine their ability to inhibit caries induction by eliminating the microorganisms which are etiological agents. This approach is based on the expectation that these bacteriocins will eradicate the causitive organisms when applied locally in the oral cavity, like antibiotics.